CN107207648A - Modified conjugated diene polymer, method for producing modified conjugated diene polymer, polymer composition, crosslinked polymer, and tire - Google Patents

Abstract

A modified conjugated diene polymer is produced by reacting a conjugated diene polymer having an alkali metal or an alkaline earth metal at the polymer terminal with a compound represented by the formula (1). R¹And R²Is a hydrocarbon group having 20 or less carbon atoms. R³Is a hydrogen atom and-CH of an alkyl group₂At least 1 of (a) a substituted alkyl group having 20 or less carbon atoms substituted with a group containing only at least one element selected from nitrogen, phosphorus, oxygen and sulfur as a hetero atom or a 1-valent aromatic group having 20 or less carbon atoms containing at least one element selected from nitrogen, phosphorus, oxygen and sulfur. Wherein R is³Has no active hydrogen. R⁴Is alkanediyl having not more than 20 carbon atoms. n is 1 or 2.

Description

Modified conjugated diene polymer, method for producing modified conjugated diene polymer, Polymer composition, crosslinked polymer and tire

technical field

The present invention relates to a modified conjugated diene polymer, a method for producing the modified conjugated diene polymer, a polymer composition, a crosslinked polymer and a tire.

Background technique

Conjugated diene-based rubbers obtained by emulsion polymerization or solution polymerization (for example, styrene-butadiene copolymers, etc.) have conventionally been known as rubbers for automobile tires. In addition, as a rubber material for tires, a conjugated diene-based rubber capable of obtaining a tire excellent in various characteristics such as low rolling resistance, abrasion resistance, fracture characteristics, and steering stability is desired. Accordingly, various techniques for modifying conjugated diene-based rubbers for use in tires have conventionally been proposed (see, for example, Patent Documents 1 to 3).

Patent Document 1 discloses the use of an alkoxysilane compound having a nitrogen-containing group in which the active hydrogen of an amino group is protected with a silyl group as a modifying agent, and a conjugated diene polymer having a polymerization active terminal and a modifying agent After the reaction, hydrolysis is performed to obtain a conjugated diene polymer having a primary amino group and an alkoxysilyl group at the polymer terminal. In addition, Patent Document 2 discloses modification of a conjugated diene polymer using N-n-butyl-aza-2,2-dialkoxysilacyclopentane. Patent Document 3 discloses obtaining a modified conjugated diene-based polymer through the following steps: a modifying agent having a total number of alkoxy groups bonded to a silyl group of 4 or more and having 1 or more nitrogen atoms and a molecular weight A step of reactive terminal reaction of conjugated diene polymers distributed within a predetermined range, and a modifying agent having a total of 2 or 3 alkoxy groups bonded to a silyl group and having one or more nitrogen atoms A step of reacting with active terminals of a conjugated diene polymer having a molecular weight distribution within a predetermined range.

prior art literature

patent documents

Patent Document 1: Japanese Patent No. 4129619

Patent Document 2: International Publication No. 2006/076629

Patent Document 3: Japanese Patent Laid-Open No. 2013-43977

Contents of the invention

When the modified conjugated diene polymer is obtained by the method described in Patent Document 1, the silanol compound generated in the production process is contained in the polymerization solvent. Treatment of the influence of alcohol compounds (for example, removal treatment, detoxification, etc.). In addition, in view of environmental conditions such as global warming due to carbon dioxide emissions in recent years, increased awareness of resource conservation and energy conservation, and economic conditions such as rising gasoline prices, rubber materials for tires are required to be low-evaluated. The low hysteresis loss characteristic, which is an index of fuel consumption performance, is excellent, and it is possible to achieve a balance with wet grip characteristics, which is one of the evaluation indexes of handling stability.

The present invention has been accomplished in view of the above-mentioned problems, and one of its objects is to provide a modified conjugated bismuth compound for obtaining rubber materials that can suppress the generation of silanol compounds and has both low hysteresis loss characteristics and wet grip characteristics in a balanced manner. vinyl polymers.

The inventors of the present invention conducted intensive studies to achieve the above-mentioned problems of the prior art, and as a result, found that the above-mentioned problems can be solved by using a polymer having a specific functional group, and completed the present invention. Specifically, the present invention provides the following modified conjugated diene polymer, its production method, polymer composition, crosslinked polymer, and tire.

One aspect of the present invention provides a modified conjugated diene polymer, which is the reaction of a conjugated diene polymer having an alkali metal or alkaline earth metal at the end of the polymer and a compound represented by the following formula (1) things.

(In formula (1), R ¹ and R ² are each independently a hydrocarbon group with 20 carbon atoms or less, R ³ is a hydrogen atom possessed by an alkyl group and at least one of -CH ₂ - contains only nitrogen , at least one of phosphorus, oxygen and sulfur as a heteroatom group substituted with a substituted alkyl group with 20 or less carbon atoms or a carbon atom group with at least 20 carbon atoms containing at least one element selected from nitrogen, phosphorus, oxygen and sulfur The following monovalent aromatic groups. Wherein, R ³ does not have active hydrogen. R ⁴ is an alkanediyl group below 20 carbon atoms. n is 1 or 2)

In another aspect, the present invention provides a method for producing a modified conjugated diene polymer, in which a conjugated diene polymer having an alkali metal or an alkaline earth metal at the end of the polymer is combined with the compound represented by the above formula (1) Compounds react.

In addition, another aspect provides a polymer composition comprising the above-mentioned modified conjugated diene polymer, silica, and a crosslinking agent. In addition, a crosslinked polymer obtained by crosslinking the polymer composition is provided. In addition, there is further provided a tire using the crosslinked polymer as a material for at least a tread or a sidewall.

The modified conjugated diene polymer obtained by modifying the end of the polymer with the compound represented by the above formula (1) can suppress the generation of silanol compounds in the production process. In addition, according to the above-mentioned modified conjugated diene polymer, it is possible to obtain a vulcanized rubber having both low hysteresis loss characteristics and wet grip characteristics required for applications such as automobile tires in a balanced manner. In addition, by using such a modified conjugated diene-based polymer, an automobile tire having both low fuel consumption performance and wet grip performance can be obtained.

detailed description

[1] Modified conjugated diene polymer

The modified conjugated diene polymer of the present invention can be obtained by reacting a conjugated diene polymer having an alkali metal or an alkaline earth metal at the end of the polymer with a specific cyclic silazane compound (A).

＜Conjugated diene polymer＞

The conjugated diene polymer in the present invention can be obtained by polymerizing a conjugated diene compound or polymerizing a conjugated diene polymer and an aromatic vinyl compound in the presence of an alkali metal compound or an alkaline earth metal compound. Examples of the conjugated diene compound used for polymerization include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene ene, 1,3-hexadiene, 1,3-heptadiene, 2-phenyl-1,3-butadiene, 3-methyl-1,3-pentadiene, 2-chloro-1, 3-butadiene, etc. Among these conjugated diene compounds, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and the like are preferable. Conjugated diene compounds can be used alone or in combination of two or more.

Examples of aromatic vinyl compounds used for polymerization include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4- Dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, 5-tert-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, three Vinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethylether, N,N-dimethylaminoethyl N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-tert-butylstyrene, 3-tert-butyl ylstyrene, 4-tert-butylstyrene, vinylxylene, vinylnaphthalene, vinylpyridine, diphenylethylene, diphenylethylene containing tertiary amino groups (for example, 1-(4-N,N- Dimethylaminophenyl)-1-phenylethylene, etc.) etc. As the aromatic vinyl compound, styrene among the aromatic vinyl compounds is particularly preferable. The aromatic vinyl compounds can be used alone or in combination of two or more.

The conjugated diene polymer in the present invention may be a homopolymer of a conjugated diene compound, but is preferably a copolymer of a conjugated diene compound and an aromatic vinyl compound from the viewpoint of improving the strength of the rubber. Among them, a copolymer containing 1,3-butadiene and styrene in the monomer composition is preferable from the viewpoint of high activity in anionic polymerization. The copolymer may be either a random copolymer or a block copolymer.

Regarding the usage ratio of the conjugated diene compound and the aromatic vinyl compound, low hysteresis loss characteristics, wet skid resistance and abrasion resistance of the cross-linked polymer obtained by cross-linking the modified conjugated diene-based polymer From the viewpoint of a good balance of properties, the proportion of the conjugated diene compound used is preferably 50 to 100% by mass, more preferably 55 to 95% by mass, based on the total amount of monomers used in the synthesis of the conjugated diene polymer. quality%. In addition, the usage ratio of the aromatic vinyl compound is preferably 0 to 50% by mass, more preferably 5 to 45% by mass based on the total amount of monomers used in the synthesis of the conjugated diene polymer.

At the time of polymerization, monomers other than the conjugated diene compound and the aromatic vinyl compound can be used. Examples of other monomers include acrylonitrile, methyl (meth)acrylate, ethyl (meth)acrylate, hydroxyethyl (meth)acrylate, and the like. The amount of other monomers used is preferably 25% by mass or less, more preferably 15% by mass or less, and still more preferably 10% by mass or less, based on the total amount of monomers used for polymerization.

As the polymerization method for obtaining the conjugated diene polymer in the present invention, any of solution polymerization method, gas phase polymerization method, and bulk polymerization method can be used, but solution polymerization method is particularly preferable. In addition, as the polymerization form, any of a batch type and a continuous type can be used. In the case of solution polymerization, as an example of a specific polymerization method, the following method can be cited: In an organic solvent, a monomer containing a conjugated diene compound is mixed with an alkali metal compound or an alkaline earth metal compound as a polymerization initiator and according to The polymerization is carried out in the presence of a vinyl content adjuster (randomizer) that needs to be used.

Specific examples of alkali metal compounds or alkaline earth metal compounds include methyllithium, ethyllithium, n-propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, phenyllithium, and stilbene lithium. , naphthyl lithium and other monolithium compounds; -Diisopropenylbenzene diadduct, 1,3,5-trilithium substituted benzene and other polyfunctional lithium compounds; and naphthyl sodium, naphthyl potassium, di-n-butyl magnesium, di-n-hexyl magnesium, ethoxy Potassium base, calcium stearate, etc. Among them, alkali metal compounds are preferable, and lithium compounds are particularly preferable.

In addition, the polymerization reaction may be performed in the presence of a compound obtained by mixing an alkali metal compound or an alkaline earth metal compound and a compound having a functional group interacting with silica. By performing polymerization in the presence of such a compound, a polymer having a functional group interacting with silica at a polymerization initiation terminal can be obtained. It should be noted that in this specification, "interaction" refers to the formation of covalent bonds between molecules or the formation of intermolecular forces weaker than covalent bonds (for example, ion-dipole interaction, dipole-dipole interaction). Electromagnetic pneumatic forces that act between molecules such as sub-substance interactions, hydrogen bonds, van der Waals forces, etc.). Examples of the "functional group interacting with silica" include groups containing at least one element selected from nitrogen, phosphorus, oxygen, silicon, and sulfur.

As a compound obtained by mixing an alkali metal compound or an alkaline earth metal compound and a compound having a functional group that interacts with silica, among them, a reaction product of a lithium compound such as an alkyllithium compound and a nitrogen-containing compound such as a secondary amine compound is preferred. metal amides. Specific examples of the nitrogen-containing compound include dimethylamine, diethylamine, dipropylamine, dibutylamine, dodecamethyleneimine, N,N'-dimethyl- N'-trimethylsilyl-1,6-diaminohexane, piperidine, pyrrolidine, hexamethyleneimine, heptamethyleneimine, dicyclohexylamine, N-methylbenzyl Amine, bis-(2-ethylhexyl)amine, diallylamine, morpholine, N-(trimethylsilyl)piperazine, N-(tert-butyldimethylsilyl)piperazine , 1,3-bis(trimethylsilyl)-1,3,5-triazine, etc.

When the polymerization is performed in the presence of a metal amide compound, the ratio of the secondary amine compound to the alkali metal compound or alkaline earth metal compound can be appropriately set according to the type of alkali metal compound or alkaline earth metal compound used. Usually, it can be set in the range of 0.1 to 1.8 mol with respect to 1 mol of metal atoms contained in the alkali metal compound or alkaline earth metal compound used for polymerization. From the viewpoint of further improving wet grip characteristics and low hysteresis loss characteristics, it is preferably 0.2 to 1.5 mol, more preferably 0.3 to 1.0.

It should be noted that when the polymerization is carried out in the presence of a polymerization initiator having a functional group, a compound prepared by mixing an alkali metal compound or an alkaline earth metal compound and a compound having a functional group that interacts with silica in advance can be added to the polymerization system . Alternatively, the alkali metal compound or alkaline earth metal compound and the compound having a functional group interacting with silica may be separately added in the polymerization system and mixed in the polymerization system.

In the said polymerization reaction, it is preferable that the total usage-amount of a polymerization initiator is 0.2-20 mmol with respect to 100 g of monomers used for polymerization. In addition, as a polymerization initiator, one of the above-mentioned ones may be used alone or two or more of them may be used in combination.

The randomizer can be used for the purpose of adjusting the content rate (vinyl bond content) of vinyl bonds (1,2-bonds and 1,4-bonds), and the like. Examples of randomizing agents include dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, 2,2-bis( Tetrahydrofuryl)propane, 2-(2-ethoxyethoxy)-2-methylpropane, triethylamine, pyridine, N-methylmorpholine, tetramethylethylenediamine, etc. These can be used alone or in combination of two or more.

As the organic solvent used for the polymerization, any organic solvent may be used as long as it is inactive to the reaction, and for example, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons and the like can be used. Among them, hydrocarbons having 3 to 8 carbon atoms are preferable, and specific examples thereof include propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propylene, 1- Butene, isobutene, trans-2-butene, cis-2-butene, 1-pentyne, 2-pentyne, 1-hexene, 2-hexene, benzene, toluene, xylene, ethyl Benzene, heptane, cyclopentane, methylcyclopentane, methylcyclohexane, 1-pentene, 2-pentene, cyclohexene, etc. In addition, as an organic solvent, it can use individually by 1 type or in combination of 2 or more types.

When solution polymerization is employed, the monomer concentration in the reaction solvent is preferably 5 to 50% by mass, more preferably 10 to 30% by mass, from the viewpoint of maintaining a balance between productivity and ease of polymerization control. The temperature of the polymerization reaction is preferably -20 to 150°C, more preferably 0 to 120°C, and even more preferably 20 to 100°C. In addition, the polymerization reaction is preferably carried out under a pressure sufficient to keep the monomer substantially in the liquid phase. Such a pressure can be obtained by a method such as pressurizing the inside of the reactor with a gas inert to the polymerization reaction.

A conjugated diene-based polymer having an alkali metal or an alkaline earth metal at the end of the polymerization can be obtained by the above-mentioned polymerization reaction. The polystyrene-equivalent weight average molecular weight (Mw) obtained by gel permeation chromatography (GPC) of the conjugated diene polymer is preferably 1.0×10 ⁵ to 2.0×10 ⁶ . If the Mw is less than 1.0×10 ⁵ , the crosslinked polymer obtained by crosslinking the modified conjugated diene polymer tends to have low heat generation and wear resistance, and if it is more than 2.0×10 ⁶ , there is The processability of a polymer composition containing a modified conjugated diene polymer tends to decrease. More preferably, it is 1.2×10 ⁵ to 1.5×10 ⁶ , and still more preferably, it is 1.5×10 ⁵ to 1.0×10 ⁶ .

From the viewpoint of achieving a good balance between the low hysteresis loss characteristic and the wet grip performance of the crosslinked polymer in the obtained conjugated diene polymer, it is preferable that the content ratio of the structural unit derived from the aromatic vinyl compound is higher than that of the conjugated diene polymer. The total amount of the structural units of the conjugated diene polymer is 0 to 50% by mass and the vinyl bond content is 20 to 90% with respect to the total amount of the structural units of the conjugated diene compound contained in the conjugated diene polymer. mole %. The content rate of the polymerized units derived from an aromatic vinyl compound is more preferably 5 to 45% by mass, and still more preferably 10 to 40% by mass. In addition, from the viewpoint of achieving both grip characteristics and wear resistance, the vinyl bond content in the structural unit of the conjugated diene compound is more preferably 25 to 85 mol%, and still more preferably 30 to 70 mol%. In addition, the vinyl bond content is the value measured by ¹ H-NMR.

＜Cyclic silazane compound (A)＞

The cyclic silazane compound (A) in the present invention is a compound represented by the above formula (1). In the above ^formula ( ¹ ), examples of hydrocarbon groups for R1 and R2 include linear or branched alkyl groups having 1 to 20 carbon atoms, cycloalkyl groups having 3 to 20 carbon atoms, carbon An aryl group having 6 to 20 atoms, an aralkyl group having 7 to 20 carbon atoms, and the like. Among them, an alkyl group or an aryl group is preferable, and a methyl group or an ethyl group is more preferable.

"A group containing only at least one heteroatom selected from nitrogen, phosphorus, oxygen, and sulfur (hereinafter also referred to as a "specific group")" for R ³ as long as it does not have active hydrogen and does not contain nitrogen, phosphorus, or A heteroatom group other than oxygen and sulfur may be sufficient. Specifically, for example, -NR ⁵ R ⁶ , -PR ⁵ R ⁶ , -O-, -S-, -S-S-, -NR ⁵ -, -PR ⁵ - (where R ⁵ and R ⁶ are each independently a hydrocarbon group having 10 or less carbon atoms) and the like. The number of the above-mentioned specific groups that the substituted alkyl group of ^R3 has is not particularly limited, and may be one or multiple. Among them, the specific group is preferably a group containing at least nitrogen, more preferably at least any one of -NR ⁵ R ⁶ and -NR ⁵ - from the viewpoint of a high effect of improving the dispersibility of silica. By. It should be noted that the part of the alkyl chain in the substituted alkyl group may be linear or branched. In the present specification, "heteroatom" means an atom other than carbon and hydrogen. "Active hydrogen" refers to a hydrogen atom bonded to an atom other than carbon, and preferably refers to a hydrogen atom having a bond energy lower than the carbon-hydrogen bond of polymethylene.

As long as the monovalent aromatic group of ^R3 is a group without active hydrogen, for example, rings of heteroaromatic compounds containing at least one element selected from nitrogen, phosphorus, oxygen and sulfur can be mentioned. Group obtained by partially removing one hydrogen atom, partially removed from the ring of a cyclic compound obtained by substituting at least one hydrogen atom of an aromatic ring (including aromatic hydrocarbons and heteroaromatic compounds) with the above-mentioned specific group 1 hydrogen atom, etc. Here, examples of heteroaromatic compounds include pyridine, pyrimidine, pyrazine, thiophene, and furan, and examples of aromatic hydrocarbons include benzene rings, naphthalene rings, and anthracyclines.

The alkanediyl group of R ⁴ preferably has 2 to 7 carbon atoms, more preferably 3 to 5 carbon atoms. In addition, n is preferably 2 from the viewpoint of interaction with silica and the viewpoint of processability when it is made into a polymer composition.

The cyclic silazane compound (A) is preferably a compound in which ^R is a substituted alkyl group, and specific examples thereof include 2-(2,2-dimethoxy-1,2-azasilacyclopentane Alkyl-1-yl)-N,N-diethylethane-1-amine, 2-(2,2-dimethoxy-1,2-azasilacyclopentan-1-yl)- N,N-Dimethylethane-1-amine, 3-(2,2-dimethoxy-1,2-azasilacyclopentan-1-yl)-N,N-diethyl Propan-1-amine, 2-(2,2-dimethoxy-1-aza-2-silacyclohexane-1-yl)-N,N-diethylethane-1-amine, etc. . In addition, cyclic silazane compound (A) can be used individually by 1 type or in combination of 2 or more types.

The reaction between the conjugated diene polymer and the cyclic silazane compound (A) (hereinafter also referred to as "terminal modification reaction") can be performed, for example, in the form of a solution reaction. This solution reaction may be performed using a solution containing unreacted monomer after the polymerization reaction is completed, or may be performed after isolating and dissolving the conjugated diene polymer contained in the solution in an appropriate solvent such as cyclohexane. This reaction can be performed using any of a batch type and a continuous type. In addition, the method of adding the cyclic silazane compound (A) is not particularly limited, and examples thereof include a method of adding together, a method of dividing and adding, and a method of continuously adding.

The usage ratio of the cyclic silazane compound (A) (the total amount when two or more kinds are used) is preferably 0.2 moles or more, more preferably 0.4 moles per mole of metal atoms involved in the polymerization reaction contained in the polymerization initiator. More than Moore. By being 0.2 mol or more, the terminal modification reaction can be sufficiently advanced, and the effect of improving fuel economy performance and wet grip performance is high, which is preferable. In addition, from the viewpoint of reducing unreacted substances in the solution after the reaction, it is preferable to make the use ratio of the cyclic silazane compound (A) less than 1.2 per mole of metal atoms involved in the polymerization reaction contained in the polymerization initiator. mol, more preferably less than 1.0 mol.

The temperature of the terminal modification reaction is usually the same as the temperature of the polymerization reaction, preferably -20 to 150°C, more preferably 0 to 120°C, particularly preferably 20 to 100°C. If the temperature of the modification reaction is low, the viscosity of the conjugated diene polymer tends to increase, and if the temperature of the modification reaction is high, the polymerization active terminal is likely to be deactivated. The reaction time of the terminal modification reaction is preferably 1 minute to 5 hours, more preferably 2 minutes to 1 hour.

In the terminal modification reaction, other compounds may be used in combination with the cyclic silazane compound (A) as a compound capable of reacting with a polymerization active terminal. The other compound is not particularly limited as long as it reacts with a polymerization active terminal and does not have an active hydrogen, and conventionally known compounds can be appropriately selected and used. Specific examples of other compounds that react with polymerizable active terminals include amino group-containing alkoxysilane compounds, glycidylamino group-containing compounds, amino group-containing (thio)carbonyl compounds, tin compounds, silicon compounds, and isocyanates. Compounds and other modifiers or coupling agents, etc. When the above-mentioned other compounds are used in the terminal modification reaction, the proportion thereof is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total amount of the cyclic silazane compound (A) and the above-mentioned other compounds.

Isolation of the modified conjugated diene polymer contained in the reaction solution can be carried out, for example, by a known desolvation method such as steam stripping and drying such as heat treatment. To the obtained modified conjugated diene polymer, if necessary, an extender oil or the like may be added to adjust the Mooney viscosity. This treatment can improve workability. As extender oil, aromatic oil, naphthenic oil, paraffin oil etc. are mentioned, for example. The compounding quantity of extender oil should just be set suitably according to the monomer used for superposition|polymerization etc., For example, it is 10-50 mass parts with respect to 100 mass parts of modified conjugated diene-type polymers. It should be noted that the modified conjugated diene polymer of the present invention may be a hydrogenated product obtained by hydrogenating a part or all of the double bonds of the conjugated diene polymer after the modification reaction. The hydrogenation reaction can be performed according to a known method.

The polystyrene-equivalent weight average molecular weight (Mw) of the modified conjugated diene polymer by GPC is preferably 1.0×10 ⁵ to 2.0×10 ⁶ , more preferably 1.2×10 ⁵ to 1.5×10 ⁶ , More preferably, it is 1.5×10 ⁵ to 1.0×10 ⁶ . In addition, the molecular weight distribution (Mw/Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 1.0 to 3.5. If the molecular weight distribution is wide, there is a tendency that low molecular weight components increase and low hysteresis loss characteristics and wear resistance decrease. More preferably, it is 1.0-3.0, More preferably, it is 1.0-2.5. According to the above-mentioned method using the cyclic silazane compound (A) as a modifier, a modified conjugated diene polymer having a sharp molecular weight distribution can be obtained, and a vulcanized rubber excellent in low hysteresis loss performance can be obtained, which is preferable. .

[2] Polymer composition and cross-linked polymer

(polymer composition)

The polymer composition of the present invention comprises a modified conjugated diene polymer obtained by reacting a conjugated diene polymer having an alkali metal or an alkaline earth metal at the end of the polymer with a cyclic silazane compound (A). (hereinafter also referred to as "specific polymer") as a polymer component. The content ratio of the specific polymer in the polymer composition is preferably 20% by mass or more, more preferably 30% by mass or more, and still more preferably 40% by mass or more, based on the total amount of the polymer composition. If the ratio is 20% by mass or more, the mechanical properties such as tensile strength and tensile elongation of the cross-linked polymer, crack growth resistance, and abrasion resistance can be improved, and the cross-linked polymer can be made low. Good fuel consumption and wet grip.

The polymer composition of the present invention may contain other polymers than the above-mentioned specific polymers as polymer components. Examples of such other polymers include natural rubber, synthetic isoprene rubber, butadiene rubber, modified butadiene rubber, styrene-butadiene rubber, modified styrene-butadiene rubber, Ethylene-α-olefin copolymer rubber, ethylene-α-olefin-diene copolymer rubber, acrylonitrile-butadiene copolymer rubber, chloroprene rubber, halogenated butyl rubber, styrene-isoprene copolymer rubber, butadiene Diene-isoprene copolymer rubber, random styrene-butadiene-isoprene copolymer rubber, styrene-acrylonitrile-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber and polystyrene Ethylene-polybutadiene-polystyrene block copolymers and their mixtures, etc.

(silicon dioxide)

The polymer composition of the invention contains silica as a reinforcing agent. Specific examples of silica include wet silica (hydrous silicic acid), dry silica (silicic anhydride), colloidal silica, precipitated silica, calcium silicate, aluminum silicate, etc. . Among these silicas, wet-type silica is particularly preferable from the standpoint of the effect of improving the fracture resistance and the balance between wet grip and low rolling resistance. In addition, it is also preferable to use a high-dispersion type (High Dispersible Type) silica from the viewpoint of enabling good dispersibility in the polymer composition and improving physical properties and processability. In addition, silica can be used individually by 1 type or in combination of 2 or more types.

In addition, the polymer composition of the present invention may contain carbon black as a reinforcing agent together with silica as needed. By using carbon black, the effect of improving the grip performance and damage resistance of the cross-linked polymer becomes greater. Specific examples of carbon black include furnace black represented by HAF, ISAF, and SAF, acetylene black, thermal black, and the like. Carbon black can be used alone or in combination of two or more.

The total amount of silica and carbon black in the polymer composition of the present invention is preferably 20 to 130 parts by mass, more preferably 25 to 100 parts by mass of the total amount of polymer components contained in the composition. 110 parts by mass. This is because if the amount of the reinforcing agent is small, the effect of improving fracture resistance and the like tends to be insufficient, and if the amount of the reinforcing agent is large, the processability of the polymer composition tends to decrease. In addition, by blending a carbon-silica dual-phase filler (Dual Phase Filler) in the polymer composition of the present invention, the same excellent advantages as when silica and carbon black are used in combination can be obtained.

(crosslinking agent)

The polymer composition of the present invention contains a crosslinking agent (vulcanizing agent). Examples of the crosslinking agent include sulfur, sulfur halides, organic peroxides, quinonedioximes, organic polyamine compounds, alkylphenol resins having a methylol group, and the like. As a crosslinking agent, sulfur is generally used. The compounding ratio of sulfur is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the total polymer components contained in the polymer composition.

The polymer composition of the present invention may further contain various agents, additives, and the like generally used in the rubber industry as desired. Examples of such agents or additives include vulcanization aids, processing aids, vulcanization accelerators, silane coupling agents, compatibilizers, process oils, antiaging agents, scorch inhibitors, zinc white, and the like.

Here, stearic acid is generally used as a vulcanization aid and a processing aid. The compounding ratio of a vulcanization aid and a processing aid is 0.5-5 mass parts normally with respect to 100 mass parts of total polymer components contained in a polymer composition.

The vulcanization accelerator is not particularly limited, and examples thereof include sulfenamide-based, guanidine-based, thiuram-based, thiourea-based, thiazole-based, dithiocarbamic acid-based, and xanthic acid-based compounds. The compounding quantity of a vulcanization accelerator is 0.1-5 mass parts normally with respect to 100 mass parts of total polymer components contained in a polymer composition, Preferably it is 0.4-4 mass parts.

As the silane coupling agent, bis(3-triethoxysilylpropyl) polysulfide, 3-trimethoxysilylpropylbenzothiazolyl tetraphenyl, etc. Sulfides and mercaptosilane compounds exemplified in JP-A-2006-249069. The compounding ratio of a silane coupling agent is preferably 1-20 mass parts with respect to 100 mass parts of silica contained in a polymer composition, More preferably, it is 3-15 mass parts.

As the compatibilizer, for example, organic compounds selected from compounds containing epoxy groups, carboxylic acid compounds, carboxylate compounds, ketone compounds, ether compounds, aldehyde compounds, compounds containing hydroxyl groups and compounds containing amino groups, and Silicon compounds and the like selected from alkoxysilane compounds, siloxane compounds, and aminosilane compounds.

The polymer composition of the present invention can be prepared by mixing the polymer component, silica, crosslinking agent, and components blended as needed using an open kneader (for example, a roll), an internal kneader (for example, a Banbury Internal mixer) and other kneading machines are kneaded and manufactured. In addition, the polymer composition of the present invention can be applied to various rubber products as a crosslinked polymer by performing crosslinking (vulcanization) after molding. Specifically, it can be applied to, for example, tire applications such as tire treads, undertreads, carcass, sidewalls, and bead portions; applications such as anti-vibration rubber, fenders, belts, hoses, and other industrial products. Among these, it can be used particularly preferably as a rubber for tire treads from the viewpoint of imparting fuel economy performance and wet grip performance.

The manufacture of tires can be carried out according to conventional methods. For example, when the above-mentioned cross-linked polymer is used for the sidewall, the above-mentioned polymer composition is mixed with a kneader, and the sheet-shaped material is arranged on the outside of the carcass according to a conventional method and vulcanized and molded, thereby forming a sidewall. Wall rubber, get air-filled tires.

Example

Hereinafter, although this invention is concretely demonstrated based on an Example, this invention is not limited to these Examples. In addition, "part" and "%" in an Example and a comparative example are a mass basis unless otherwise indicated. The measurement methods of various physical property values of the polymer are as follows.

- Bonded styrene content [%]: Measured by ¹ H-NMR at 500 MHz.

- Vinyl bond content [mol%]: Measured by ¹ H-NMR at 500 MHz.

- Weight average molecular weight (Mw): Under the following conditions, the retention time corresponding to the apex of the maximum peak of the GPC curve obtained using gel permeation chromatography (trade name "HLC-8120GPC", manufactured by Tosoh Corporation) Calculated in terms of polystyrene.

Column: 2 pieces of product name "GMHXL" (manufactured by Tosoh Corporation)

Column temperature: 40°C

Mobile phase; tetrahydrofuran

Flow rate; 1.0ml/min

Sample concentration; 10mg/20ml

[Comparative example 1]

＜Synthesis of modified conjugated diene polymer PC1＞

2150 g of cyclohexane as a solvent, 0.5 mmol of tetrahydrofuran as a randomizer, 135 g of styrene as a monomer, and 1,3-butanediene were placed in a nitrogen-substituted autoclave reactor with an internal volume of 5 liters. Alkene 355g. After adjusting the temperature of the contents of the reactor to 10° C., 4.57 mmol of n-butyllithium (n-BuLi) was added as a polymerization initiator to initiate polymerization. The polymerization was carried out under adiabatic conditions, reaching a maximum temperature of 90°C. When the polymerization conversion rate reached 99%, 10 g of 1,3-butadiene was added over 2 minutes, and then 2,2-dimethoxy-1-phenyl- 1,2-Azasilacyclopentane (a compound represented by the following formula (b-1)) was 4.14 mmol, and the reaction was terminated after 15 minutes.

Next, 2.0 g of 2,6-di-t-butyl-p-cresol was added to the obtained polymer solution. Next, the solvent is removed by steam stripping to obtain a modified conjugated diene polymer. Then, the obtained polymer was dried using a heat roll adjusted to 110° C. to obtain a modified conjugated diene polymer PC1.

＜Manufacture of polymer composition and cross-linked polymer＞

Using the modified conjugated diene polymer PC1 obtained above, each component was compounded according to the compounding recipe shown in the following Table 1, and it was kneaded, and the polymer composition was manufactured. Kneading was performed by the following method. Using a jet mill with a temperature control device (inner capacity: 250ml), first, as the first stage of kneading, the modified conjugated diene polymer was blended at a filling rate of 72% and a rotation speed of 60rpm. PC1, butadiene rubber, extender oil, silicon dioxide, carbon black, silane coupling agent, stearic acid, anti-aging agent and zinc oxide for mixing. Next, as the second stage of kneading, after cooling the compound obtained above to room temperature, sulfur and a vulcanization accelerator were mixed and kneaded. This was molded and vulcanized at 160° C. for a predetermined time in a vulcanization press to obtain a crosslinked polymer (vulcanized polymer).

[Table 1]

In Table 1, the trade names used for each component are as follows.

*1: BR01 by JSR Corporation, *2: JOMOProcess NC-140 by Japan Energy Corporation, *3: ZEOSIL 1165MP by Rhodia Corporation, *4: DIA Black N339 by Mitsubishi Chemical Corporation, *5: Si75 by Evonik Corporation, *6 : Ozonon 6C manufactured by Seiko Chemical Co., Ltd. *7: Nocceler D manufactured by Ouchi Shinko Chemical Co., Ltd. *8: Nocceler CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

＜Physical property evaluation＞

The physical property evaluation shown below was performed about the crosslinked polymer obtained above.

(1) tanδ at 0°C

The crosslinked polymer was used as a measurement sample, and the measurement was performed under conditions of a shear strain of 1.0%, an angular velocity of 100 rad/s, and 0° C. using ARES-RDA (manufactured by TA Instruments). The measurement result was shown by the index which made the comparative example 1 into 100, and evaluated by comparing with each index of the Example mentioned later. The larger the numerical value, the better the wet grip characteristics.

(2) 50℃tanδ

The cross-linked polymer was used as a measurement sample, and ARES-RDA (manufactured by TA Instruments Co., Ltd.) was used for measurement under the conditions of a shear strain of 1.0%, an angular velocity of 100 rad/s, and 50°C. The measurement result was shown by the index which made the comparative example 1 into 100, and evaluated by comparing with each index of the Example mentioned later. The larger the value, the smaller the energy loss and the better the low hysteresis loss characteristic.

[Example 1]

<Synthesis and evaluation of modified conjugated diene polymer P1>

In addition to changing the polymerization terminator used to 2-(2,2-dimethoxy-1,2-azasilacyclopentan-1-yl)-N,N-diethylethane-1- Except that the amine (compound represented by the following formula (A-1)) was 4.14 mmol, polymerization was carried out in the same manner as in Comparative Example 1 to obtain modified conjugated diene polymer P1. In addition, using the modified conjugated diene polymer P1, a polymer composition and a crosslinked polymer were prepared in the same manner as in Comparative Example 1, and physical properties were evaluated. The results are shown in Table 2 below together with the measurement results of the bonded styrene content, the vinyl bond content, and the weight average molecular weight of the modified conjugated diene polymer P1.

[Example 2]

<Synthesis and evaluation of modified conjugated diene polymer P2>

In the autoclave reactor, except that 3.31 mmol of piperidine was further charged together with a solvent, a randomizer, and a monomer, polymerization was carried out in the same manner as in Example 1 to obtain a modified conjugated diene polymer P2. In addition, using the modified conjugated diene polymer P2, a polymer composition and a crosslinked polymer were prepared in the same manner as in Comparative Example 1, and their physical properties were evaluated. The results are shown in Table 2 below together with the measurement results of the bonded styrene content, the vinyl bond content, and the weight average molecular weight of the modified conjugated diene polymer P2.

[Table 2]

According to the results in Table 2, the polymer (Example 1, 2) obtained by using the compound represented by the above formula (1) as a polymerization terminator was passed through the polymer that did not use the compound represented by the above formula (1) as a polymerization terminator. A comparison of polymers (Comparative Example 1) yielded good results in terms of wet grip characteristics and low hysteresis loss characteristics. From this, it can be seen that the method of obtaining a modified conjugated diene-based polymer using the compound represented by the above formula (1) can obtain a compound that does not generate silanol compounds in the production process and can have low hysteresis loss characteristics in a balanced manner. and wet grip properties of cross-linked polymers.

Claims (7)

1. A modified conjugated diene polymer, which is a reactant of a conjugated diene polymer having an alkali metal or an alkaline earth metal at the end of the polymer and a compound represented by the following formula (1), In formula (1), R ¹ and R ² are each independently a hydrocarbon group having 20 or less carbon atoms, R ³ is a hydrogen atom contained in an alkyl group, and at least one of -CH ₂ - is selected from nitrogen, A substituted alkyl group with at least 20 carbon atoms substituted by a heteroatom group containing at least one of phosphorus, oxygen, and sulfur, or a substituted alkyl group with at least 20 carbon atoms containing at least one element selected from nitrogen, phosphorus, oxygen, and sulfur A monovalent aromatic group, wherein ^R3 does not have active hydrogen, R4 is an alkanediyl group with ²⁰ or less carbon atoms, and n is 1 or 2. 2. The modified conjugated diene polymer according to claim 1, wherein the content ratio of the structural unit derived from the aromatic vinyl compound is relative to the total amount of the structural unit of the conjugated diene polymer 0 to 50% by mass, and the vinyl bond content is 20 to 90 mol% with respect to the total amount of structural units of the conjugated diene compound contained in the conjugated diene polymer. 3. The modified conjugated diene polymer according to claim 1 or 2, which has a nitrogen-containing functional group at a polymerization initiation terminal of the conjugated diene polymer. 4. A method for producing a modified conjugated diene polymer, wherein a conjugated diene polymer having an alkali metal or an alkaline earth metal at the end of the polymer and a compound represented by the following formula (1) are carried out reaction, In formula (1), R ¹ and R ² are each independently a hydrocarbon group having 20 or less carbon atoms, R ³ is a hydrogen atom contained in an alkyl group, and at least one of -CH ₂ - is selected from nitrogen, A substituted alkyl group with at least 20 carbon atoms substituted by a heteroatom group containing at least one of phosphorus, oxygen, and sulfur, or a substituted alkyl group with at least 20 carbon atoms containing at least one element selected from nitrogen, phosphorus, oxygen, and sulfur A monovalent aromatic group, wherein ^R3 does not have active hydrogen, R4 is an alkanediyl group with ²⁰ or less carbon atoms, and n is 1 or 2. 5. A polymer composition comprising the modified conjugated diene polymer according to any one of claims 1 to 3 or the modified conjugated diene polymer obtained by the production method according to claim 4 Olefinic polymers, silica and crosslinkers. 6. A crosslinked polymer obtained by crosslinking the polymer composition according to claim 5. 7. A tire using the crosslinked polymer according to claim 6 at least as a material for a tread or a sidewall.